The prior art is replete with different techniques and processes for fabricating semiconductor devices such as metal oxide semiconductor (MOS) transistors. In accordance with typical fabrication techniques, a MOS transistor is formed by creating a device structure on a semiconductor substrate, where the device structure includes a gate stack formed on a layer of semiconductor material, and source and drain regions that define a channel region under the gate stack. In addition, embedded stress or strain elements (i.e., doped/undoped semiconductor material that stresses the channel region) can be used to improve the performance of MOS transistors. These stress elements or stressor regions are typically formed by creating recesses in the semiconductor material on both sides of the channel region. Thereafter, the recesses are filled with a different type of semiconductor material that imparts compressive or tensile stress on the channel region. For n-type MOS transistors, tensile stressor regions improve the mobility of electrons in the channel region. Conversely, for p-type MOS transistors, compressive stressor regions improve the mobility of holes in the channel region.